000
FXUS63 KTOP 020534
AFDTOP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1134 PM CST Sun Mar 1 2015
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Monday)
Issued at 341 PM CST SUN MAR 1 2015
By this afternoon the mid-level trough axis stretched across the
Northern Plains with water vapor imagery showing a closed-off low
situated right off the California coastline. At the surface, high
pressure was advancing into the area from the north, gradually
advecting drier air into northern Kansas. Weak forcing remained in
place across east central Kansas and further south during much of
today, resulting in lingering light precipitation through
mid-afternoon in the form of a snow/sleet/freezing drizzle mix.
With the dry air advection from the light northwesterly winds,
overcast skies began to scatter out across northern Kansas this
afternoon, resulting in temperatures reaching into the low/mid 30s.
The center of the surface high pressure will track over the region
tonight into Monday morning, resulting in light winds overnight.
Soundings show some lingering mid-level clouds but still expect low
temperatures to drop to around 20 degrees tonight. The combination
of light winds and some fresh snow may support the development of
some patchy fog overnight and toward sunrise Monday, with the better
chances possibly over portions of east central Kansas. While the HRRR
is trying to hint at this potential some, soundings seem to show
minimal low-level saturation. Confidence is too low to warrant a
mention in the forecast at this time, but it is something worth
monitoring this evening.
Monday should remain dry as models have kept the deepening mid-level
trough axis west of the Rockies with any embedded shortwaves staying
west of the forecast area. However, cannot completely rule out the
potential for some patchy drizzle as model soundings show some
increasing saturation in the low-levels by Monday afternoon ahead of
the next approaching storm system, along with some isentropic lift
present. Confidence in the amount of saturation during the afternoon hours
is too low to mention in the forecast at this time, but it`s another
part of the forecast worth keeping an eye on. As winds shift and
increase out of the southeast and the cloud cover tries to scatter
out some, have increased temperatures a bit with highs in the upper
30s. However, if we end up seeing more breaks in the cloud cover, then
readings may end up reaching into the low 40s.
.LONG TERM...(Monday Night through Sunday)
Issued at 341 PM CST SUN MAR 1 2015
A cutoff upper low off the coast of southern CA will phase with a
northern stream upper trough digging southeast out of western Canada on
Monday. The resulting positive tilt H5 trough will move east into the
high plains by Tuesday evening.
A lee surface low will deepen across western KS Tuesday night.
Southwesterly 850mb and surface winds will bring warmer temperature
and richer moisture northeastward across the CWA Tuesday night. Both
the NAM and ECMWF develop the stronger isentropic lift south and
west of the CWA Tuesday evening...thus the CWA may remain dry
Tuesday evening when surface temperatures may be near or slightly
below freezing across much of the CWA. Temperatures will gradually
warm into the mid 30s by midnight as the richer moisture begins to
advect northeast towards the CWA. My thoughts are that any drizzle
or light rain will not begin until after midnight early Wednesday
morning. However, if the quicker GFS verifies, then stronger
isentropic lift will develop across eastern KS during the early
evening hours causing patchy freezing drizzle or light freezing rain
to develop, especially north of I-70. The instability looks too weak
for any elevated thunderstorms across the southeast counties of the
CWA, as the deeper moisture will remain southeast of the CWA.
Tuesday, As the positive tilt H5 trough approaches the high plains,
the 850mb winds will begin to veer more to the west through the
morning and afternoon hours. The deeper moisture will shift well
east of the CWA across eastern MO through the day. The surface low
across western KS during the morning will move northeast into
western IA. The CWA will be dry slotted with any light rain in the
early morning hours moving rapidly off to the northeast. Strong
low-level CAA across the northern and central plains Tuesday morning
will cause a cold front to push southeast across the CWA during the
afternoon hours. Tuesday high temperatures will occur in the late
morning and early afternoon hours with temperatures falling through
the day. Winds behind the front will switch to the northwest at 15
to 25 MPH with gusts to 35 MPH.
Tuesday night there may be enough ascent ahead of the positive tilt
trough for some light snow showers or flurries. There could be a
dusting of snow. The southern end of the H5 trough across TX will
amplify and may cause significant snow and ice accumulations for
parts of OK, AR and southern MO on Wednesday. A cold surface high
will build southward across the CWA Wednesday Afternoon and
Wednesday night. Highs on Wednesday will only reach the mid to upper
20s.
The upper level flow will become more zonal through the remainder of
the extended forecast. Expect dry conditions with highs warming into
the 40s on Friday and 50s by next weekend.
&&
.AVIATION...(For the 06Z TAFs through 06Z Monday Night)
Issued at 1128 PM CST SUN MAR 1 2015
Still have some mvfr visibilities at the terminals toward sunrise
but should not last long. Winds becoming south and increasing
through the remainder of the period along with mid level clouds.
Could see some light precipitation toward the end of the forecast
but too early and not enough confidence to add at this time.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Hennecke
LONG TERM...Gargan
AVIATION...67